Inverter question (1 Viewer)

[G-RMPS]

I’m not too “hot” on electrons, so this may be a dumb question.

Can an inverter be installed in such a way that it uses the exising van wiring to distribute the 240v to existing sockets, rather than plugging stuff directly into the inverter box. I have an EBL, two leisure batteries, no solar. I am considering a beefy inverter, say 2kw.

Cheers...Keith

 

[PeterCarole29]

yes it could but its too complicated for me to explain what you need to do it.

 

[HandyAndy]

yes but the pins on the outside of the vehicle plug would be live when the inverter is on.
You would need to install an auto or manual changeover switch to prevent that.
Also connected to the 240v circuit would be the battery charger, so this would need isolating at the same time other wise it would try charging the batteries because it would think it was on hook up.
Can be wired into the same change over switch mentioned above.
Other than that, yes perfectly feasible and something I am am doing when funds allow.
I had bought some LiFePo4 battery cells from the USA to make up a large battery to power the inverter from but the shipping company refused to post them so to the UK so had to get a refund on that lot. so the project has gone no further currently

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[G-RMPS]

I suppose you could plug a cable into the inverter with the other end plugged into the EHU point, though the battery charging circuit would have to be isolated somehow.

 

[HandyAndy]

I suppose you could plug a cable into the inverter with the other end plugged into the EHU point, though the battery charging circuit would have to be isolated somehow.

If the battery locker / inverter locker is close to the EHU point then yep, sounds like a good work around.
Disabling the battery charger "should" be a simple case of pulling the fuse or buying one of those fuse break out leads and fitting a switch into the circuit.

 

[Stealaway]

I have two sockets wired separately and permanently plugged into the invertor. Saves any complications and simply switch to existing sockets when on ehu

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[Robert Clark]

I suppose you could plug a cable into the inverter with the other end plugged into the EHU point, though the battery charging circuit would have to be isolated somehow.

This wouldn’t work as the inverter would then be powering the fridge and possibly the water heater too.

In our van the inverter powers all the sockets. We fitted a Victron inverter / charger which automatically kicks in when the EHU is disconnected.

 

[Richard n Ann]

You can get these 20a switches on Amazon. Commonly listed as generator changeover switches. Ours is double pole 3 position EHU - off - Inverter.

The charger is always off and I make sure the fridge and water heater are off before going over to inverter. Manual works best for us because I change over to ehu for Ann's hair dryer, plus I don't want a relay or concactor humming away all day. If it's switched over fast the TV doesn't even go off

 

[eddie]

I’m not too “hot” on electrons, so this may be a dumb question.

Can an inverter be installed in such a way that it uses the exising van wiring to distribute the 240v to existing sockets, rather than plugging stuff directly into the inverter box. I have an EBL, two leisure batteries, no solar. I am considering a beefy inverter, say 2kw.

Cheers...Keith

yes very simply.

Locate the wire(s) that lead from the distribution board (trips) to your 13amp sockets put a mains relay in series, with the N/C contacts on the mains input, piggy backed to energise the coil. Connect the N/O contacts to the inverter output

The “load” side of the relay connect to the wire(s) that supply the 13 amp sockets

As you are introducing a potentially lethal power source after the original RCD you must put a secondary RCD in series after the relay

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[pappajohn]

Yes, as explained by handyandy in post #3.... But, a 2kw inverter, if used anywhere near its full potential, will hammer your batteries and unless you intend going on hookup the next day you have no real means of topping up the batteries.

If used at its maximum output it will draw 166 amps per hour.
With a pair of 110ah batteries that's around 40 minutes use before the batteries NEED recharging and split charge (driving), your only other charging option, will take many hours.
Consider a smaller inverter and a solar panel or B2B charger.

 

[G-RMPS]

Ok, thanks everyone for the guidance. I understand the draw on the batteries, but I was particularly looking for a wiring solution. Probably best to see if I can route an extension lead to somewhere suitable, then I don’t need to bother about technicalities.

 

[Baycott]

This is a good resource posted by @Techno and it works well
https://www.motorhomefun.co.uk/forum/resources/auto-changeover-relay-for-inverter.11/

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[JeanLuc]

You said in your first post that you are ‘not too “hot” on electrons’. Unless you are confident about what you plan to do, I would respectfully suggest you get a qualified person to install it for you - such as Vanbitz.
Also, if you really intend to use the full capacity of a 2 kw inverter, you will be drawing something around 175 amps and that will drag down 2 typical leisure batteries in well under an hour. You might get 30minutes if you are lucky (from fully charged).

 

[Gellyneck]

Wasn't it much easier when all we had was a gas mantle \ Tilley lamp and a good book!
Sorry Keef!

 

[G-RMPS]

You said in your first post that you are ‘not too “hot” on electrons’. Unless you are confident about what you plan to do, I would respectfully suggest you get a qualified person to install it for you - such as Vanbitz.
Also, if you really intend to use the full capacity of a 2 kw inverter, you will be drawing something around 175 amps and that will drag down 2 typical leisure batteries in well under an hour. You might get 30minutes if you are lucky (from fully charged).

Understood! This is an expensive solution to a daily five-minute hair-drying exercise, with the bonus of charging laptops etc.

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[Baycott]

Understook


Understood! This is an expensive solution to a daily five-minute hair-drying exercise, with the bonus of charging laptops etc.

Oh yes, many of us have been there

 

[Conal]

When we had RoadPro install our inverter they offered two setups. Either an auto switch that gave us 240v on all sockets when on site electric, or separate dedicated sockets. As the inverter comes with two 240 sockets attached we went for just one extra socket next to the microwave so that we can swop the plug over to the inverter when “off grid” and have a multi socket extension permenantly plugged into the inverter. As the inverter is under the bench seat behind the driver’s seat this is not inconvenient.
We decided on this option to protect our habitat warranty.

 

[Bart]

Ok, thanks everyone for the guidance. I understand the draw on the batteries, but I was particularly looking for a wiring solution. Probably best to see if I can route an extension lead to somewhere suitable, then I don’t need to bother about technicalities.

@G-RMPS In our MH I did a per the resource by @Techno which boycott was kind enough to link. And it works great for us.

This is a good resource posted by @Techno and it works well
https://www.motorhomefun.co.uk/forum/resources/auto-changeover-relay-for-inverter.11/

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[jemhorn]

Had mine set with a selection of 220v sockets 'on' including the A/C. I used to use via EHU but power was grabbed by the fridge, charger etc. Had it sorted by local company

 

[olley]

I ran the output from the inverter direct to the electrical locker, so I just plug the ehu into it, battery charger has a switch to turn it off and I can tell the fridge to run on gas, all 7 of the 230v work along with the numerous 110v ones.

 

[GPW]

I’m not too “hot” on electrons, so this may be a dumb question.

Can an inverter be installed in such a way that it uses the exising van wiring to distribute the 240v to existing sockets, rather than plugging stuff directly into the inverter box. I have an EBL, two leisure batteries, no solar. I am considering a beefy inverter, say 2kw.

Cheers...Keith

The main question is:
What do you want to power with the inverter?

2kW from a 12V battery is 2000/12 = 167 Amps, quite a huge load. Also all inverters are not created equal, it really is a case where you get what you pay for, aim for a respected european brand.

The wiring is simpler and better if you replace the van's charger for an 'inverter-charger' such as a Victron unit which does all the EHU monitoring and switching, but it does all get rather complicated, especially if your mains fusebox has more than one circuit on it.

A competent campervan oriented electrician should be able to fit one for you however.

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[Jaws]

Understood! This is an expensive solution to a daily five-minute hair-drying exercise, with the bonus of charging laptops etc.

A little facetious I know, but there is always the option of a towel for hair..and
Laptop chargers that work on 12v ( basically they are a tiny inverter that come with a selection of plugs to fit all sorts of laptops ) for under £20

 

[Lenny HB]

Wired my van so it auto switches info here.

Also 2 batteries nowhere near enough for a 2k inverter I would want double that.

 

[GPW]

Most stuff is easy for an inverter, but suddenly demanding 2kW while still keeping a decent (high quality waveform and efficient) system gets WAY more complex. First you really have to understand what you are doing and Second - it gets very expensive for any kind of reliability and quality of mains waveform (which some items will demand!).

I'd advise going for a 500VA Victron-Multi Inverter-charger (to replace the existing charger only) and forget about 2kW, as stated above a towel and hairbrush will be fine offgrid, she can always use a hairdryer while on EHU.

That should give you a decent mains performance from a single battery for charging eBikes, laptops, cameras, toothbrushes and running a mains TV etc. Then add 100W-200W of solar for extended off grid days if you need it.

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[tonka]

Ok, thanks everyone for the guidance. I understand the draw on the batteries, but I was particularly looking for a wiring solution. Probably best to see if I can route an extension lead to somewhere suitable, then I don’t need to bother about technicalities.

I have a short extension lead from the socket of my inverter and wired to this plug, added the 12v supply off battery at same time. Does the job I need ..

 

[two]

I’m not too “hot” on electrons, so this may be a dumb question.

Can an inverter be installed in such a way that it uses the exising van wiring to distribute the 240v to existing sockets, rather than plugging stuff directly into the inverter box. I have an EBL, two leisure batteries, no solar. I am considering a beefy inverter, say 2kw.

Cheers...Keith

In simple terms, for simple folk, it cannot be done.
Take a dedicated socket from the inverter.
I'd negotiate a smaller hair dryer, say 1000W (or less) and it will become significantly easier.

 

[autorouter]

Locate the wire(s) that lead from the distribution board (trips) to your 13amp sockets put a mains relay in series, with the N/C contacts on the mains input, piggy backed to energise the coil. Connect the N/O contacts to the inverter output

I hesitate to question someone so experienced, but shouldn't that be the other way round? When the relay is not energised, you want the inverter to be connected to the sockets, so that's through the N/C contacts. When the relay is energised by the EHU mains, you want the sockets to switch over from the inverter to the EHU mains, so that's through the N/O contacts.

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[eddie]

I hesitate to question someone so experienced, but shouldn't that be the other way round? When the relay is not energised, you want the inverter to be connected to the sockets, so that's through the N/C contacts. When the relay is energised by the EHU mains, you want the sockets to switch over from the inverter to the EHU mains, so that's through the N/O contacts.

Lol,what did I write?

Just re-read you are right, I am wrong lol

In essence if the relay fails or inverter fails default is back to original

 

[PeteH]

I ran the output from the inverter direct to the electrical locker, so I just plug the ehu into it, battery charger has a switch to turn it off and I can tell the fridge to run on gas, all 7 of the 230v work along with the numerous 110v ones.

Not dissimilar to the system I used in the second R-V. But That one had 6 Batteries. and 400W of Solar, and a 220V-50hz x 40W "Smart" charger.

BTW. this site has a section about Inverter usage.: http://www.aandncaravanservices.co.uk/

 

[GPW]

In essence if the relay fails or inverter fails default is back to original

This is the correct DIY method, but a proper inverter-charger does it better. I'll give Victron as an example but all decent brands should do this:

The 500 Multi series will detect if the incoming mains is within the correct safe range before it gets used - so too low or too high and it stops using it.
The 800 and upwards Multi series support Boost and Fade, which means it will re-process mains that is a bit too low or high into the correct voltage so it works exactly as a high-end computer UPS delivering clean power within spec regardless of what goes in!
(The 800 and upwards can also be paralleled for more power with a synchronising bus cable as an aside).

So a relay is fine, but a proper product is always better for the reasons stated above!

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